At the start of a convention and several workshops in Zagreb for SDP candidates for the local polls, Milanovic called on the electorate to vote for the SDP which he described as the biggest and the best Croatian party.
He said that the SDP had the best people and programmes for taking the country out of crisis and criticised the ruling Croatian Democratic Union (HDZ) for caring "for corporations' interests" far from the eyes of the public.
Milanovic said that Croatians were facing unemployment and corruption and that his party had programmes and people that could cope with those problems.
According to him, opting for the SDP means opting for decentralisation of Croatia.
Milanovic reiterated that SDP advocated Croatia's European Union membership.
Croatia is expected to hold local elections in mid-May.